1. Field of the Invention
This invention relates generally to looped lift cords of the type used in window coverings such as pleated shades, venetian blinds and Roman shades, and more particularly, the invention relates to safety devices used with such lift cords.
2. Description of the Prior Art
Pleated shades, Roman shades and venetian blinds typically have window covering material or blind slats extending between a headrail and bottom rail and two or more lift cords connected to the bottom rail. Within the headrail is some type of cord locking device. Typically, two or more lift cords are connected at one end to the bottom rail, and extend up through the window covering material or blind slats into the headrail. The lift cords then pass through a cord locking device and out of the headrail such that an opposite end of the lift cords is accessible to an operator. These window shades and blinds are typically raised by the operator pulling on the accessible portion of the lift cords and are lowered by releasing the lift cords. Because all lift cords must move in unison, the lift cords are typically tied together or otherwise looped as can be seen in FIG. 1. The lift cords often extend downward from the headrail to within a few feet of floor level.
A second type of lift mechanism for window coverings has a spool within the headrail to which the lift cords are attached. The window covering is raised and lowered by winding and unwinding the lift cords around the spool. A continuous looped cord is provided around one end of the spool. The spool is rotated by pulling on one of the two sides of the loop depending upon whether clockwise or counter-clockwise rotation is desired. Although this lift mechanism operates differently from the first described mechanism, a window covering containing this second type of mechanism would also look very similar to the window covering shown in FIG. 1. This type of lift mechanism is disclosed in my U.S. Pat. No. 5,184,660.
Looped lift cords extending from a window treatment such as is shown in FIG. 1 present an attractive danger to infants or children who may play with the lift cords. There have been several instances in which children and infants have become entangled in such cords and accidentally hanged.
In the past, attempts to reduce the danger associated with these lift cords have focused on moving the lift cords out of the accessible range of infants such as by tying or clipping the cords to shorten them or otherwise moving the lift cords away from floor level and away from the infant's reach. Moving the cords out of the way after use is troublesome, and the operator must remember to move the cords after each use. Other attempts have focused on a detachable connection of the ends of the lift cords such as is disclosed in U.S. Pat. No. 4,909,298 to Langhart et al. Detachable lift cords require a certain level of force to detach. Moreover, recent tests of the commercially available embodiment of the Langhart patent have shown that this product failed to detach in simulated entanglements. Moreover, a detachable tassel cannot be used with the spool type lift mechanism which requires continuous rotation of the looped cord around the spool.
Thus, there is a need in the industry for a safety device to reduce the danger associated with looped lift cords which is reliable and which does not require any separate actions by the operator. Such a device must operate efficiently, yet be aesthetically pleasing. It must be inexpensive and easy to install, particularly on window coverings which are hanging in a window.
The cords used for the first type of lift mechanism are typically made of woven cotton polyester materials. For the spool type lift mechanism the looped cord may be woven or may be a bead chain. There is a need for a safety device which can be used with both woven cords and bead chains.